Place the bacon grease in a saucepan over medium-high heat. Add the onions and sauté until the onions start to blacken.
While the onions are caramelizing, in a mixing bowl place the water, honey and red wine vinegar. Using a wire whisk, mix the ingredients well.
Add the cornstarch and whisk well.
After the onions have caramelized, add the Dijon mustard to the onions and stir together with a rubber spatula.
Add the water, vinegar, pepper (sic.) honey and cornstarch to the mustard and onions and mix. Continue stirring until mix thickens and comes to a boil.
Remove from heat and store in refrigerator
until needed. To reheat use a double boiler